Three Questions. Input Needed!

[CHEMMINS 10+ year member]

No...you have to fluff the polyfil in order to make it work. If the fibers are all in hard balls, they can't vibrate, therefore they can't create heat.

 

[SmartAsss 10+ year member]

Incorrect.....you are thinking of the pillow like polyfil which it isn't. A pillow is contained. It will absorb reflecting waves and also take up volume. It isn't going to let the fibers inside the pillow vibrate enough to create enough heat to do the "box fooling".

How would having a thin porous cotton cover be any different? sound will still waves pass right through without restriction... even if they didn't pass through the cover the pillow would still compress and slow down the sound waves. which is the opposite of what he needs to do. non-compressible mass is what is needed to remove volume from the enclosure. your logic is just plain wrong, sorry.

 

[CHEMMINS 10+ year member]

How would having a thin porous cotton cover be any different? sound will still waves pass right through without restriction... even if they didn't pass through the cover the pillow would still compress and slow down the sound waves. which is the opposite of what he needs to do. non-compressible mass is what is needed to remove volume from the enclosure. your logic is just plain wrong, sorry.

Think what you will. It is proven.

Your theory would stand that if I crammed 10 pillows in a 2 cube box that there would be no displacement which is wrong.

 

[solidcrowd 10+ year member]

Either way, I can't decrease volume because I would need to make the port longer to allow for the same tunning. My enclosure is 15" deep and my port is already 11.25" long. There wouldn't be enough clearence.

 

[SmartAsss 10+ year member]

I would really like to see you try to jamb 10 pillows into 2cf... yes it will take up volume(when compressed into a solid mass like that), but then you won't have any ventilation around the sub. poly fill would work if you melted it down then solidified it into a solid brick. It would probably take 10 pillows melted down into a brick to equal the mass of one small piece of wood.

Think what you will. It is proven.

where is this proof you speak of? please enlighten me to this new found use of poly-fill.
If you can understand that then your helpless... this is just ridiculous. I cannot even believe I'm actually having to try to explain this.

 

[SmartAsss 10+ year member]

Either way, I can't decrease volume because I would need to make the port longer to allow for the same tunning. My enclosure is 15" deep and my port is already 11.25" long. There wouldn't be enough clearence.

well if you don't have the subsonic filter like i mentioned, then your only option is to build/buy a new box to proper specs.

 

[solidcrowd 10+ year member]

I have a subsonic filter...I'm gunna try to wire it to 4ohm and see if it sounds better

 

[CHEMMINS 10+ year member]

I would really like to see you try to jamb 10 pillows into 2cf... yes it will take up volume(when compressed into a solid mass like that), but then you won't have any ventilation around the sub. poly fill would work if you melted it down then solidified it into a solid brick. It would probably take 10 pillows melted down into a brick to equal the mass of one small piece of wood.
where is this proof you speak of? please enlighten me to this new found use of poly-fill.

If you can understand that then your helpless... this is just ridiculous. I cannot even believe I'm actually having to try to explain this.

You sir are lost as to what I am saying.

And your theory of mass displacing volume is uneducated as well. A 3" square chunk of lead would have more mass than 20 square inches of wood.....yet would displace less.

 

[SmartAsss 10+ year member]

You are right about the mass of wood and lead, I guess that the word mass is not what I'm looking for. lead would, have more mass. Im looking for a word that describes something that would take up volume without the ability to compress or vibrate.. displacement like you said.

fluffy poly-fill does not possess the characteristics to increase displacement without a large compressed quantity of it.

I still stand by my statement that a small piece of wood would displace more than a large quantity of poly fill. Trust me im not being thick headed, I spent some time yesterday trying to figure out your reasoning. An experiment of melting down a pillow's worth of poly fill will prove my point. not saying that either of us will do that experiment but the proof is there. poly fill has its use as increasing the volume not useful in decreasing it.

 

[CHEMMINS 10+ year member]

Yes polyfil by itself will theoretically make the sub think it is in a bigger box.....that I agree with and always have.

A pillow is stuffed though and is a totally different cat....it will slow down standing waves, making for better sq. And because it is tightly encased, it will displace volume. Hell an empty pop bottle with a lid on it will displace volume.

 

[SmartAsss 10+ year member]

take up volume without the ability to compress or vibrate..

I know for a fact that a pillow compresses, I sleep on one every night. a plastic bottle does too..
Since that happens, then it is taking energy away from the back wave, thus slowing the wave down.. making the box appear larger.

we are trying to make the back pressure more intense so we need something that does not take energy away from the sound wave. something that does not compress at all.

a pillow case is physically nothing to a sound wave, simple test would be to hold the case in front of the a speaker and listen, if you can still hear the sound then sound waves are penetrating it.

I cannot explain this anymore clearly, is it sinking in yet? Sorry op for polluting this post.